They were to dock at the orbiting outpost six hours later, but the booster suffered a failure minutes after the launch.

The two made an emergency landing in Kazakhstan at an unspecified time. Search and rescue crews scrambled to reach the expected landing site.

It’s the first space mission for Hague, who joined NASA’s astronaut corps in 2013. Ovchinin spent six months on the station in 2016.

Relations between Moscow and Washington have sunk to post-Cold War lows over the crisis in Ukraine, the war in Syria and allegations of Russian meddling in the 2016 U.S. presidential vote, but Russia and the U.S. have maintained cooperation in space.